1. Field of the Invention
Exemplary embodiments of the present invention relate to an apparatus and method for controlling a geostationary orbit satellite, and more particularly, to an apparatus and method for controlling an orbit and a pose of a geostationary orbit satellite to avoid collisions with space debris in an inclined geosynchronous orbit while keeping in a geostationary orbit normally.
2. Description of the Related Art
A geostationary orbit satellite appears to be in a fixed position when viewed from a particular location on the Earth because the geostationary orbit satellite has an orbital period equal to the rotation period, 23 hours 56 minutes 4 seconds, to that of the Earth. For this reason, geostationary orbit satellites are widely used for communication, broadcasting, Earth observation, global positioning system (GPS) augmentation, and the like. The geostationary orbit satellite is positioned about 36,000 kilometers (km) above the Equator, and has an inclination close to zero degrees.
To prevent mutual interference and physical collision between satellites, the geostationary orbit satellite occupies a predetermined area, and a limited number of geostationary orbit satellites is allowed for one particular orbit. Also, an international registration/notification procedure for allocation of a predetermined frequency in satellite communication is established to prevent potential interference conflicts.
Generally, the lifespan of a geostationary orbit satellite is ten to fifteen years, and is dependent on a supply of fuel supply needed to maintain a location in a predetermined area. According to international regulations, a de-orbiting strategy is recommended. A satellite may be de-orbited to re-enter an altitude of 200 km or higher at the end of a lifespan using the residual fuel, to make room for a new satellite.
Currently, a considerable amount of space debris, also known as space waste, is floating in orbit around the Earth. A majority of space debris consists of dead or inoperable geostationary orbit satellites remaining in orbit due to re-entry failure. Other pieces of debris are fragments of rocket bodies used to place geostationary orbit satellites into orbit.
By the effects of various perturbations such as, for example, the asymmetrical gravitational field of the Earth, gravitational attraction of the moon and the sun, and solar radiation pressure, space debris may transfer to an inclined and eccentric geosynchronous orbit.
The orbit inclination gradually increases to 15 degrees and reverts to 0 degrees over a 53 year period. Space debris in an inclined geosynchronous orbit passes through the equatorial plane of the Earth twice each sidereal day. Accordingly, when space debris approaches a geostationary orbit satellite working normally, a collision may occur. To resolve this collision issue, performing orbital maneuvers for a geostationary orbit satellite is needed to ensure a safe distance from space debris.